Bitumen and its applications
Bitumen, a product of a crude oil refining process, is a mixture of various hydrocarbons that occur naturally. Bitumen is used in roofing, sealing, and insulation; the most common application is in road pavement. Bitumen serves as a binder for the mineral components (rocks) in the upper asphalt (concrete) layers of roads, parking lots, runways, etc. Roads are exposed to heavy traffic and a wide range of weather conditions, leading to undesired effects such as the formation of grooves or cracks. New asphalt concrete formulations that are more durable and withstand increasing traffic loads as well as extreme weather conditions are needed.
The rheological properties of bitumen binder play an important role in the development of new formulations. A set of rheological testing protocols have been defined over the past several decades to guarantee consistent quality control of bitumen binder materials. The most common rheological testing methods are described below.
SHRP superpave performance grading
- Used for asphalt binder specification according to AASHTO M320/ AASHTO T315 or ASTM D7175/ ASTM D6373
- Measuring geometry: 8 or 25 mm parallel plates
- Temperature range: between 4 °C and 88 °C
- Measuring mode: oscillation test within linear-viscoelastic range at a frequency of 10 rad/s (1.59 Hz)
- Performed on original and RTFOT / PAV aged asphalt binder
- Information obtained:
Multiple stress creep recovery test
- According to AASHTO T350, ASTM D7405, DIN EN 16659 or FGSV AL 723
- Measuring geometry: 25 mm parallel plates
- Temperature range: between 50 °C and 80 °C
- Measuring mode: multiple creep and recovery tests at two different stress values (0.1 and 3.2 kPa)
- Performed on original and RTFOT / PAV aged asphalt binder (RTFOT aged sample for performance grading)
- Results can be used for performance grading according to AASHTO M332
- Information obtained:
Viscosity determination of asphalt binder at elevated temperatures
- According to AASHTO T316, ASTM D4402, DIN EN 13702
- Measuring geometry: coaxial cylinder
- Temperature range: up to 200 °C*
- Measuring mode: shear viscosity determination at constant rotational speed
- Testing is performed with unaged original binder
- Information obtained:
- Viscosity provides information about behavior during mixing, pumping, and application of asphalt binder
*Higher temperature possible with electrical temperature control module
- AASHTO TP 123 (Measuring asphalt binder yield energy and elastic recovery)
Two types of tests with either monotonic shear for an extended period or a shorter period of monotonic shear followed by an extended relaxation process. - DIN EN 14770 (Determination of complex shear modulus and phase angle)
Oscillatory tests over a wider range of frequencies and temperatures. - FGSV AL 720 (Binder fast characterization test)
Measurement of the complex shear modulus and the phase angle in a temperature range from 20°C to 90°C. - FGSV AL 722 (Testing with constant shear rate)
Rotational test at constant shear rate in a temperature range from 150 °C to 70°C. - FGSV AL 724 – Temperature Sweep
Determination of the complex shear modulus and phase angle at different temperatures 30 °C and 90 °C.
Understand the rheological behavior of bitumen at the molecular level:
- Simultaneous rheological and FTIR spectra measurements
- ATR (attenuated total reflection) principle
- Analysis of structural changes on the molecular level under shear/deformation and temperature
- All standard-compliant bitumen measurement routines are also available
- AASHTO TP123 BYET
- AASHTO T315 SHRP-Test
- AASHTO M320 Standard Specification for Performance Grading - SHRP
- AASHTO T316 Rotational viscosity with cylinder
- AASHTO T350 MSCR-Test
- AASHTO M332 Standard Specification for Performance Grading - MSCR
- ASTM D4402 Rotational viscosity with cylinder up to 200 °C
- ASTM D7175 SHRP-Test
- ASTM D7405 MSCR-Test
- DIN EN 13302 Rotational viscosity with cylinder
- DIN EN 13702 Rotational viscosity with cone & plate
- DIN EN 14770 Complex modulus and phase angle
- DIN EN 16659 MSCR-Test
- FGSV AL 720 BTSV-Test
- FGSV AL 721 Constant Shear Rate
- FGSV AL 722 Temperature Sweep
- FGSV AL 723 MSCR-Test
- Other standards available on request
Featured instruments for bitumen rheology
